In humans, the in-mouth perception of dietary fat in food is a complex process involving many sensory modalities (texture, aroma, taste and trigeminal). During food oral processing, a bolus is formed in which saliva is significantly incorporated thus contributing significantly to the perception of fat. In particular, it has been shown that the levels of some salivary characteristics (lipolysis, lysozyme, flux, antioxidant status, level of carbonic anhydrase and proteins) are related to the sensitivity of the individual to triolein and oleic acid. Interestingly, the involvement of some of these salivary variables in the perceived intensity and preference towards model oil emulsions was also shown. In addition to fat perception and preference, recent results show an indirect relation between these salivary components, BMI and post-prandial lipid metabolism in human subjects. It is hypothesized that this relationship should be linked to a difference in fat sensitivity and liking according to the BMI. The role of saliva as a key factor in fat perception in one side and post-prandial lipid metabolism in another side is discussed.